How to Build a 3d Map of Dark Matter

We have an idea for where we think dark matter should be based on where all the galaxies are. We then take careful pictures of them to try to estimate how much each one is distorted. And then it's com ing that to our idea forwhere we think the dark matter shouldbe. It looks like dark matter of more spread out than we expected, instead of being in these thin strands between galaxies. Some ot the denser blobs of dark matter did form enough stuff to create galaxies and stars. The kind of strands we're talking about between galaxies is a smaller fraction of the amount of dark matter. Dark matter also varies in density out there, absolutely.